Active matrix organic light-emitting diode (AMOLED) is widely used due to its advantages such as wide viewing angle, excellent color contrast, rapid response and low cost. A driving thin film transistor (TFT) drives the AMOLED to emit light through a current generated in a saturation state. Due to the lack of uniformity and stability during the manufacturing of a back plate of the TFT, threshold voltage (Vth) drift will occur in the driving TFT. The driving current for lightening the AMOLED is associated with the threshold voltage of the driving TFT. When the threshold voltage drift occurs in the driving ITT and different AMOLEDs receive an identical data voltage (Vdata), the current for driving it to emit light will vary. As a result, an entire image will be displayed non-uniformly.